Preparation And Characterization Of The Nano Solis Lipid Particles Loaded UVA/UVB Sunscreens

Nano solid lipid particles as a new type of carrier systerm have been gradually applied in medicine, cosmetics and food, and other fields. As the coating carrier in cosmetic, on the one hand can enhence the stability of active ingredients, on the other hand can realize the controlled release. Thus the nano solid lipid particles was worth of promotion.The UVA/UVB sunscreens loaded nano solid lipid particles(NLCs) were prepared by homogeneous-ultrasonication method. The UVA/UVB sunscreens were respectively butylmethoxydibenzoylmethane(BMBM) and octylmethoxycinnamate (OMC). Cetyl stearic ether-20, hydrogenated castor oil and caprylic/capric triglyceride were used as the solid emulsifier, solid lipid and liquid lipid in this experiment, respectively. Process condition and formulation were optimized by Box-Behnken design. The optimized preparation process was ultrasonication time 14.57min, ultrasonication power 756.25W, emulsifier tempreture 87.92 ℃. The optimum formulations for minimum particle size, maximum EE of OMC and maximum EE of BMBM were 6.5%(w/w) GTCC,2.0%(w/w) Cutina HR and 5.0% (w/w) Eumulgin B2. Correspondingly, the particle size, EE of OMC and EE of BMBM were 315.29 nm,99.75% and 87.414%, respectively.The optimal formulation was characterized by scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, infrared spectroscopy. On the basis, sunscreen ability, photostability and centrifugation stability of NLCs and common emulsions were compared. The configuration of the naono solid lipid particles was spherical and the surface was smooth. There was no aggregation. The sunscreens were loaded in the nano solid lipid particles and the crystal form was unchanged three months later. SPF of UVA/UVB-loaded NLCs and a common emulsion were 41.43 and 33.43, respectively. The photostability of sunscreens were improved compared to the conventional emulsion. There was a synergistic effect of the nano solid particles and the sunscreen performance was enhanced. The UVA/UVB-loaded NLCs would not layered after centrifugation 30min,9000r/min.Finaly, the effects of moisturizer (glycerol, HA and betaine) and rheology(carbomer 980, carbomer 941, AVC and xanthan gum) on the nano solid lipid particles were studied. The addition of moisturizer and rheology had an effect on the particle size PDI and stability, but have no effect on the structure.